I have to commit blasphemy and disagree with the official order given (by Joss, apparently) on the BBC's site. This may be the order they were filmed in or something, but Heart of Gold is CLEARLY the "End of Season" episode.

Objects in Space is fantastic and probably my favorite episode, but Heart of Gold is obviously ...

Doyce: according to a earlier link here, Whedon did some minor editing to OiS when it was clear that the three other episodes were not going to be aired. (The original version of OiS should appear on the DVD.)